This invention relates to poly(arylene ether) polymers, and more particularly to grafting functional groups to the backbone of poly(arylene ether) polymers to provide cross-linkable polymers that crosslink at low temperatures and have particular utility as a dielectric, passivation, insulating, or, super high aperture enhancing material with high glass transition temperatures and low moisture uptake.
The electronics and display industries have sought low dielectric materials for use in fabricating fine dimension integrated circuits and less finely dimensioned thin film transistors for flat panel displays and medical imaging. However, the need for materials compatibility and dimensional stability over a wide range of conditions not only during ultimate end use, but also during further processing conditions leading to the finished integrated circuits and thin film transistors, has presented a significant problem. The problem has been to make a polymeric thermoset system that meets the mechanical property requirements of these applications, but also cure at relatively low temperatures. This problem has been a very difficult one to solve, particularly for high Tg polymers where the desired temperature for reaction (i.e., cure) is at or below 300° C. and more preferably below 250° C. It is also desirable to induce crosslinking by UV radiation so that the dielectric polymer is photoimageable.
There is also a need in the electronic, display, and medical imaging fabrication industries for the replacement of silicon-based, dielectric or insulating materials with materials of lower dielectric values. Silica and its modified versions have dielectric values on the order of 3.0 to 5.0 and usually 4.0 to 4.5. Polymeric materials used as replacements for silica as interlayer dielectric materials can have dielectric constant values in the range of 1.9 to 3.5, with values that are highly dependent on the structure of the polymeric materials. To successfully replace silicon-based dielectric and insulating materials, the properties of polymeric materials must conform to the rigid manufacturing requirements for integrated circuits or microchips in the electronic fabrication industry or for passivation or super high aperture enhancement in organic or silicon-based thin film transistors employed for flat panel displays, sensors, and medical imaging. Crosslinking has been recognized as one way to address the requirements of electronic, display, and imaging materials polymers.
Past attempts utilized various different approaches for crosslinking polymers. A detailed summary of these attempts is provided in the inventor's U.S. Pat. No. 6,060,170, assigned to Air Products & Chemicals, Inc. This patent teaches the use of poly(arylene ether) polymer compositions having aromatic groups grafted on the poly(arylene ether) backbone, which grafts allow for crosslinking of the polymers in a temperature range of 200 to 450° C.
U.S. Pat. Nos. 5,179,188 and 5,114,780 to Mercer et al. also disclose poly(arylene ether)-based polymers. These patents teach that fluorinating the backbone of such polymers provides a dielectric material with superior properties. However, the use of fluorinated arylene groups in the backbone of the polymer introduces functional reactive groups, which in turn deteriorate insulating and moisture adsorption properties.
Integrated circuit, chip, display, and imaging manufacturing require suitable coatings. These coatings are required to have low dielectric constants. In addition, it is desirable to provide these coatings with unlimited storage stability at 25° C., storage stability at 40° C. sufficient to weather transportation in non-refrigerated vehicles, and cure temperatures of 200 to 300° C. within 1 to 2 hours. After cure, it is desired to have a Tg in the range of 200 to 300° C., a dielectric constant below 3.5 with frequency independence, and a maximum moisture absorption of less than 1 wt %.
All references cited herein are incorporated herein by reference in their entireties.